Gel Filtration Chromatography. Experiment 5 BCH 333 [practical]
5 Filtration
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FiltrationChapter 4 in Fundamentals
Professor Richard Holdich
Course details:
Particle Technology,
module code: CGB019 and CGB919,2nd year of study.
Watch this lecture at
http://www.vimeo.com/10201620
Visit
http://www.midlandit.co.uk/particletechnology.htm
for further resources.
mailto:[email protected]://www.vimeo.com/10201620http://www.midlandit.co.uk/particletechnology.htmhttp://www.midlandit.co.uk/particletechnology.htmhttp://www.vimeo.com/10201620mailto:[email protected] -
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Filtration
Types
Cake filtration mechanism
Modification of Darcy's law
Constant pressure filtration
Constant rate filtration
Variable rate & pressure filtration
Industrial equipment
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Types of filtration
Normally batch (in duplicate)but some continuous ones:
Deep bed -clarification
Image supplied by DynaSand and Hydro International (Wastewater) Ltd.
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Types - membrane
Clarification on filtering membranes
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Types - Clarification
Cartridge and candle filtration
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Cake filtration mechanism
Multifilament filter cloth p. 40
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Cake filtration mechanism
Monofilament filter cloth
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Cake filtration mechanism
Monofilament open filter cloth/mesh
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Cake filtration mechanism
p.31
Why cant we simply measureRm
for each medium?
Ideal
Filtrate
Bridgingover pores
Filter medium
Filter cake
sharp interface medium/cake - uniform spheresin cake easy to model
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Cake filtration mechanism
reality p 41
Why cant we simply measureRm
for each medium?
Real
Filter cake
Filter medium
i.e.Rm = f(material to be filtered)
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Modification of Darcy's law Porosity or voidage
and Concentration
dV
dt
1
A
Porous media
void + solid = unity
fraction fraction
Volume fractions:
U =o
Uo
U
Superficial velocity:
+ C = 1
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Modification of Darcy's lawDarcys law:
At
V
kL
P 1
d
d
Kozeny-Carman equation:
AtVS
LP v 1
dd)1(5 3
22
Pressure/L
Flow rate
xSv
/6
use:
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Modification of Darcy's lawDarcys law/Kozeny:
At
V
kL
P 1
d
d
Pressure/L
Flow rate
What do the graphs tell us about these equations?
How will this vary for filtration?
Think about a given material and filter in these equationswhat is constant, what varies, look at the graph
What are the independent and dependent variables?
A
QSv
3
22)1(5
Time
Volume
liquid
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Modification of Darcy's law p.29
Darcys law:
At
V
kL
P 1
d
d
Q is constant
- permeation
Time
Filtrate
volumeQ decreases- filtration
At constant pressure drop:
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Modification of Darcy's law p. 32Build up of incompressible filter cake:
Filter medium
Filter cakeformation
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Modification of Darcy's law
20 kPa
P = dV 1L k dt A
1.5 V
V = R I
0.75 V10 kPa
0 kPa 0 V
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Modification of Darcy's lawPressure drops are additive:
Pcake
Pmedium
AtV
kL
1
d
d
At
V
k
L
m
m 1
d
d
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Modification of Darcy's lawPressure drops are additive:
PAt
V
k
L 1
d
d
At
VRm
1
d
d
00
Gradient:
Ca
kevolum
e
Filtrate volume
= LAV
Ratio:
cake volume:filtrate = constant =
PARV
kCC
PAVt m
s
s
2
d
d
PA
RV
PA
c
V
t m
2
d
d
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Modification of Darcy's law
00
Gradient:
Ca
kevolum
e
Filtrate volume
= LAV
Ratio:
cake volume:filtrate = constant =
1
sC
What does
Represent in English,see the graph
skC
1
What does
Represent in English
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Modification of Darcy's law p.36where cis the dry cake mass per unit volume of filtrate:
and is the specific resistance to filtration (m/kg).
smsc
1
sis feed slurry mass fraction andmis the moisture ratio of thecake (mass cake wet/mass cake dry - or sample). In someinstances one can assume m=1; i.e. neglect liquid in cake.
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Modification of Darcy's law
p.36
AQRRP mc /)(
w
Rc
alpha =Rc/w
ConsideringRc& alpha some more:
w is dry mass/unit area solids:
A
cVw
so:
AQR
A
cVP m /)(
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Modification of Darcy's law equation (4.11)
sm
sc
1
PARV
PAc
Vt m
2
dd
General filtration equation:
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Constant pressure filtrationConstant P filtration - integrate general equation:
to give:
PA
RV
PA
c
V
t m
2
d
d
PA
RV
PA
c
V
t m
2
2
baVV
t
i.e:
Time over filtratevolume
Filtrate volume
b
a
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Constant pressure filtrationsummary: Need to know:
PA
RV
PA
c
V
t m
2
2
viscosity, pressure,and filter area
& slurry massfraction, liquiddensity (and cakemoisture - if poss.)
Time over filtratevolume
Filtrate volume
b
a
Need to calculate:
c then
andRm
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Constant pressure filtration General filtration equation:
Constant pressure:
PARV
PAc
Vt m
2
2
PA
RV
PA
c
V
t m
2
d
d
y = m x + c
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Constant pressure filtration Filtration Testing in the Laboratory:
effect of pressure,
different cloths or media,
slurry agitation, filter aids and flocculants
effect of slurry pre-concentration
High permeability: vacuum leaf Low permeability: pressure bomb
Tests:
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Constant pressure filtration Filtration Testing in the Laboratory:
specific resistance - possibly as f(pressure),
medium resistance
cake concentration - possibly as f(pressure)or moisture ratio
High permeability: vacuum leaf Low permeability: pressure bomb
To obtain values of:
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Constant pressure filtration Filtration Testing in the Laboratory:
Liquid viscosity
filtration pressure
filter area
High permeability: vacuum leaf Low permeability: pressure bomb
Also required for scale-up or simulation:
Slurry mass fraction
liquid density
solid density - if cakeheight is required
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Constant pressure filtrationp. 41 vacuum filter leafTo vacuum
pump
Calibrated
filtratereceiver
Drain
Leaf or
Mechanical
agitation
Vent
Valve - fully open in test
Slurry tank
Filtering side
Buchner
Stirrer
funnel
Experimental characterisation
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Constant pressure filtration
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Constant rate filtration p. 36
Constant rate:
General filtration equation:
PA
RV
PA
c
V
t m
2
d
d
t
V
A
RV
t
V
A
cP m
2
V
t
t
V
d
d
Filtrationpressure
Filtrate volume
b
a
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Variable rate & pressurefiltration General filtration equation:
Variable pressure and rate equation:
PA
RV
PA
c
V
t m
2
d
d
A
RV
A
c
Q
P m
2
plot numerical integration of:V
Q&
1
QV
td
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Industrial equipment p. 35Rotary vacuum filter (continuous)
Stages cake formation in slurrytank (F)
drying and/or washing
(D and W)
discharge - then back toformation (D & Di)
F
D
W
D & Di
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Industrial equipment Constant pressure:
PA
RV
PA
c
V
t m
2
2
Rearrange for a quadratic:
02
2
2
tV
PA
RV
PA
c m
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Industrial equipment p. 36 Simulation of Rotary Vacuum Filter:
02
2
2
tV
PA
RV
PA
c m
i.e. aV2 + bV- t= 0
a
atbb
V 2
42
where form timet = F/n(submergence/speed)
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Industrial equipment per cycle of drum:
Mass dry cake deposited = cV(kg) Mass wet cake deposited = mcV (kg)
mass slurry filtered = mcV+ V (kg)
a
atbbV
2
42
Calculate volume, hence:
All above is per cycle, hence 3600/tfor output per hour.
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Industrial equipmentVacuum belt filter (continuous)
Image appearscourtesy ofPolyfilters UKLimitedwww.polyfilters.com
http://www.polyfilters.com/http://www.polyfilters.com/ -
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Industrial equipment
Vacuum belt
filter(continuous)
Image supplied courteousy of BHS-Sonthofen GmbH, Germany www.bhs-sonthofen.de
http://www.bhs-sonthofen.de/http://www.bhs-sonthofen.de/http://www.bhs-sonthofen.de/http://www.bhs-sonthofen.de/ -
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Industrial equipmentVacuum disc filter (continuous)
Image courtesy of FLSmidth, Inc.
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Industrial equipmentTube pressure filter (batch)
Image courtesy of Mesto Minerals (Sala) AB
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Filtration
Types
Cake filtration mechanism
Modification of Darcy's law
Constant pressure filtration
Constant rate filtration
Variable rate & pressure filtration
Industrial equipment
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This resource was created by Loughborough University and released as an open educational resource through the Open EngineeringResources project of the HE Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCEand part of the JISC/HE Academy UKOER programme.
Slide 3. Image of a DynaSand is provided courtesy of Hydro International (wastewater) Limited. See http://www.hydro-international.biz/irl/wastewater/dynasand.php formore details.
Slide 37. The image of a vacuum belt filter (continuous is provided with the permission of Polyfilters (UK) Limited. See http://www.polyfilters.com/process.html for moredetails.
Slide 38. Image provided courtesy of BHS-Sonthofen GmbH. See www.bhs-sonthofen.de for more details.
Slide 39. Image provided courtesy of FLSmidth Inc. Seehttp://www.flsmidthminerals.com/Products/Filtration/Vacuum+Filtration/Vacuum+Disc+Filters/Agidisc+Vacuum+Filters/Agidisc+Vacuum+Filters.htm for more details.
Slide 40. Image of a tube press discharge, provided courtesy of Mesto Minerals (Sala) AB. Seehttp://www.metso.com/miningandconstruction/MaTobox7.nsf/DocsByID/C44A6B216E52C95142256AF6002D6148/$File/Tube_Press_ES.pdf for more details.
2009 Loughborough University
This work is licensed under a Creative Commons Attribution 2.0 License.
The name of Loughborough University, and the Loughborough University logo are the name and registered marks of Loughborough University. To the fullest extentpermitted by law Loughborough University reserves all its rights in its name and marks, which may not be used except with its written permission.
The JISC logo is licensed under the terms of the Creative Commons Attribution-Non-Commercial-No Derivative Works 2.0 UK: England & Wales Licence. Allreproductions must comply with the terms of that licence.
The HEA logo is owned by the Higher Education Academy Limited may be freely distributed and copied for educational purposes only, provided that appropriateacknowledgement is given to the Higher Education Academy as the copyright holder and original publisher.
http://www.hydro-international.biz/irl/wastewater/dynasand.phphttp://www.polyfilters.com/process.htmlhttp://www.bhs-sonthofen.de/http://www.flsmidthminerals.com/Products/Filtration/Vacuum+Filtration/Vacuum+Disc+Filters/Agidisc+Vacuum+Filters/Agidisc+Vacuum+Filters.htmhttp://www.metso.com/miningandconstruction/MaTobox7.nsf/DocsByID/C44A6B216E52C95142256AF6002D6148/$File/Tube_Press_ES.pdfhttp://creativecommons.org/licenses/by/2.0/uk/http://creativecommons.org/licenses/by/2.0/uk/http://www.metso.com/miningandconstruction/MaTobox7.nsf/DocsByID/C44A6B216E52C95142256AF6002D6148/$File/Tube_Press_ES.pdfhttp://www.flsmidthminerals.com/Products/Filtration/Vacuum+Filtration/Vacuum+Disc+Filters/Agidisc+Vacuum+Filters/Agidisc+Vacuum+Filters.htmhttp://www.flsmidthminerals.com/Products/Filtration/Vacuum+Filtration/Vacuum+Disc+Filters/Agidisc+Vacuum+Filters/Agidisc+Vacuum+Filters.htmhttp://www.flsmidthminerals.com/Products/Filtration/Vacuum+Filtration/Vacuum+Disc+Filters/Agidisc+Vacuum+Filters/Agidisc+Vacuum+Filters.htmhttp://www.bhs-sonthofen.de/http://www.bhs-sonthofen.de/http://www.bhs-sonthofen.de/http://www.polyfilters.com/process.htmlhttp://www.hydro-international.biz/irl/wastewater/dynasand.phphttp://www.hydro-international.biz/irl/wastewater/dynasand.phphttp://www.hydro-international.biz/irl/wastewater/dynasand.phphttp://creativecommons.org/licenses/by/2.0/uk/http://engsc.ac.uk/an/oer-project/oer-project.asphttp://www.jisc.ac.uk/http://engsc.ac.uk/